Water relief valve for a drainage system



FIG. 1 is a perspective view of a water relief valve for a drainage system showing our new design in the open position;

FIG. 2 is a perspective view of our new design in the closed position;

FIG. 3 is a top plan view thereof;

FIG. 4 is a bottom plan view thereof;

FIG. 5 is a side elevational plan view thereof, the opposite side being a mirror image thereof, showing our new design in the open position;

FIG. 6 is a side elevational view thereof, the opposite side being a mirror image thereof, showing our new design in the closed position;

FIG. 7 is a bottom perspective view of our new design in the closed position;

FIG. 8 is a bottom perspective view of our new design in the open position; and,

FIG. 9 is a vertical medial sectional view of our new design as shown in FIG. 5. 

The ornamental design for a water relief valve for a drainage system, as shown and described. 